On recent high-performance passenger cars, a low aspect ratio tire which is excellent in steering stability, grip performance and structural durability at a high speed is widely used. In particular, for a sports car in which high speed performance is of special importance, tires with an aspect ratio less than 55% are now becoming used.
In such a low aspect ratio tire, a weight reduction is further required to achieve a further improvement in car performance, e.g. running performance, low fuel consumption and the like.
In conventional pneumatic tires, as shown in FIG. 13, each bead portion is provided with a bead apex C between a carcass main portion A and a carcass turned up portion B in order to increase the bending rigidity of the bead portion and thereby improve the steering stability of the tire. The bead apex C is made of hard rubber and extends radially outwardly from the bead core into the sidewall portion over the radially outer edge of the rim flange. Thus, the bead apex has a considerable volume and weight.